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Fundamentals of Communication Networks Prof. A. Pattavina V exam – 2 September 2020 Surname and name: (upper case) Signature: (your readable signature) Matricola ID: Pag. 1/6 1 - Exercise* (8 points) Consider the packet switching network shown below with 4 hosts (H, A, B, C) and 6 links ( wired between routers and outgoing from host H, wireless entering hosts A, B, C). Source H starts transmitting at time t = 0 a sequence of six packets addressed to destinations A, A , C, B, B, A. These packets are denoted, respectively, as A1, A2, C1, B1, B2, A3. All routers (R1, R2, R3) are store&forward routers and their packet processing time is negligible. Assume that all packets have a fixed size L=128 byte. • Draw on a time diagram the sequence of transmissions by the source H and by each router showing the arrival time at each destination • Fill up the table below indicating the initial transmission (tx) time of each packet node by node • Express the time when each packet is completely received at respective destination, indicating such times as TA1, TA2, TC1, TB1, TB2, TA3 (denote by Tx and τx the transmission time and propagation time on link x = 1,2,3,4,5,6) • Compute numerically TA1, TA2, TC1, TB1, TB2, TA3 and fill up the last column of table below Packet Start tx in H Start tx in R1 Start tx in R2 Start tx in R3 End receiving at destination A1 TA1,H= TA1,R1= TA1,R2= TA1= A2 TA2,H= TA2,R1= TA2,R2= TA2= C1 TC1,H= TC1,R1= TC1,R2= TC1= B1 TB1,H= TB1,R1= TB1,R2= TB1,R3= TB1= B2 TB2,H= TB2,R1= TB2,R2= TB2,R3= TB2= A3 TA3,H= TA3,R1= TA3,R2= TA3= * R1 R2 A CB C1 = 512 kbit/s l1= 200 km C2 = 0.341 Mbit/s l2 = 600 km C4 = 256 kbit/s l4 = 400 km C6 = 512 kbit/s l6 = 300 km C3 = 256 kbit/s l3 = 600 kmH C5 = 512 kbit/s l5 = 600 km R3 Fundamentals of Communication Networks Prof. A.…